This invention relates in general to improvements in wheel assemblies of the type used with wheelchairs and other devices. More particularly, this invention relates to an improved caster wheel assembly having an adjustable caster swivel post for varying the angle of the caster swivel post to ensure that the caster swivel post remains in a vertical orientation. Moreover, this invention relates to an improved rear wheel assembly having an adjustable axle for varying the camber angle of the axle.
Caster wheel assemblies in general are well known in the art for use with many different types of castered devices. Such caster wheel assemblies are commonly employed as the front wheels in a typical wheelchair. Each caster wheel assembly typically includes a caster fork, which rotatably supports a relatively small diameter caster wheel, and which further includes a generally upright caster swivel post captured by appropriate caster post bearings for rotation about a swivel axis within a fixed cylindrical housing. The fixed housing is adapted in turn for mounting onto frame components of the wheelchair, or other castered device. Such caster wheel assemblies beneficially provide a high degree of turning maneuverability.
The caster swivel post defines a vertically oriented axis about which the caster fork rotates. The caster post bearings are typically used to provide a smooth, frictionless pivot. The caster wheel is rotatably supported by the caster fork via a caster wheel axle, which is situated rearward with respect to the caster swivel post. This ensures that the caster wheel axle is always trailing the caster swivel post in the direction of travel. The rearward offset distance of the caster wheel axle with respect to the caster swivel post is commonly referred to as the “rake”. The caster swivel post must be oriented vertically to ensure that the caster wheel remains in contact with a supporting surface as the caster fork pivots about the caster swivel post. This vertical orientation ensures that the caster wheel will not lift off the supporting surface while turning.
Wheelchairs and other castered devices typically incorporate a number of adjustments, including wheel height adjustment, wheel camber adjustment, and wheel size adjustment. Such adjustments are common with regard to the rear wheels of the wheelchair to allow a wheelchair occupant to customize the wheelchair to his or her anthropometry or driving conditions. When any of these adjustments are made, the angle of the caster swivel post changes and must also be adjusted to ensure that the caster swivel post remains vertical. Various means have been used to achieve caster swivel post angle adjustment, and are currently available on the market. Such means are typically bulky, heavy, and cumbersome for the user to adjust.
What is needed is an improved adjustable wheel assembly having a unique means for providing adjustability and that is a very compact, lightweight, and easy for the user to adjust.